1. Field of the Invention
The present invention relates to a wireless signal transmitting and receiving technique, and more particularly to a pulse data coding method for wireless signal transmitting and receiving devices, with which a pulse data signal transmitted by a transmitting device is protected against interference by noise signals and can therefore be correctly received by a corresponding receiving device.
2. Description of the Prior Art
It is a common practice in many electronic apparatus to transmit a signal of the electronic apparatus to a nearby receiving device by means of wireless transmitting/receiving technique, so that the electronic apparatus is more practical for use without being limited by a signal wire or cable. For example, most of the currently very popular exercise apparatus include a sensor to detect the user's heart rate, so that a signal of the detected heartbeat rate is processed by a transmitter and wirelessly sent in the form of a heartbeat pulse signal to a nearby receiver via a radio carrier, enabling the user to timely and properly control his or her body condition while taking exercises.
In the conventional pulse data wireless transmitting and receiving techniques, the pulse data may be sent in several different forms, including single pulse, long duration pulse, dual pulse/multiple pulse, coded pulse, etc. FIG. 1 illustrates waveforms of a heartbeat signal S10 detected by a transmitter and transmitted in different forms of single pulse S11, long duration pulse S12, double pulse/multiple pulse S13, and coded pulse S14 through conventional wireless signal transmitting technique, and FIG. 2 shows different waveforms of the heartbeat signal S10 received by a receiver when the heartbeat signal S10 is transmitted in different forms of single pulse S11, long duration pulse S12, double pulse/multiple pulse S13, and coded pulse S14 through conventional wireless signal transmitting technique without being interfered by noise signals.
However, it is almost impossible to avoid interferences by noise signals in real application of the wireless transmitting and receiving techniques. FIG. 3 shows the waveforms of the heartbeat signal S10 received by a receiver when the pulse signal S10 is transmitted in different forms of single pulse S11, long duration pulse S12, double pulse/multiple pulse S13, and coded pulse S14 through conventional wireless signal transmitting technique under interferences by noise signals, which are generally denoted by Sn. When a pulse data signal is transmitted in the form of single pulse S11 using conventional wireless transmitting technique, a receiver interfered by noise signals Sn from, for example, a motor, a television set, an alternating power line, a computer, or a radio communication equipment, is completely not protected against such interferences with the transmitted signals, and could not correctly receive the signals transmitted by a corresponding transmitter.
When the pulse data signal is transmitted in the form of long duration pulse S12 using conventional wireless transmitting technique, it is possible to protect the long duration pulse signal S12 against part of existing noise signals. However, the receiver would not be able to avoid the interferences by the noise signals Sn when the noise signals Sn come from an interference source having a considerably high intensity. In addition, the long duration pulse S12 would disadvantageously consume higher power.
When the pulse data signal is transmitted in the form of dual pulse/multiple pulse S13 using conventional wireless transmitting technique, it is possible to protect the dual pulse/multiple pulse signal S13 against part of existing noise signals Sn. However, the receiver would not be able to discriminate real signals from false signals when the receiver is subjected to interferences from a continuous interference source, such as interference signals from an alternating power supply of 60 Hz or other frequencies.
When the pulse data signal is transmitted in the form of coded pulse S14 using conventional wireless transmitting technique over high-frequency carrier or ultrahigh-frequency carrier, the signal may usually be ideally transmitted. However, when the pulse data signal is transmitted in the form of coded pulse S14 using conventional wireless transmitting technique over low-frequency carrier, such as 5 KHz or 10 KHz, problems of insufficient bandwidth and high probability of signal corruption due to noise signals would exist. In addition, the transmission of pulse data signals in the form of coded pulse S14 also has the disadvantage of high power consumption and is therefore not an optimum way in transmitting pulse date signals.